Method of preparing crucibles for preparing fused quartz.



EYES. S FOR PREPARING FUSED QUARTZ.

ED APR. 3. 19].)-

Patented Dec. 11, 1917.

' METHOD OF PREPARING CRUCIBLE APPLICATION m 1, ,637.

[Ni/ENTOR til dti

tit!

UNI ED STATES PATENT OFFICE" I EEEnEnIcK e. KEYEs, or HoEoKEiv, NEWJERSEY, assrsivoa Tocoor E HEWITT ELECTRIC COMPANY, or HOBOKEN, NEWJERSEY, a CORPORATION OF NEW JERSEY.

lan'rnon or PREPARING oitucIELEs Eon PREPARING EusEn QUARTZ.

Specification of Letters Patent. Patentedljec, 11, 1917, tlriginalapplication filed July 1, 1913, Serial No. 776,756. Divided and th isapplication filed April 8, 1915.

Serial No. 19,921.

To all whom it may concern." Be it known that I, FREDERICK GrfKEYEs, acitizen of the United States, and resident of Hoboken, county of Hudson,State of New Jersey, have invented certain new and useful Improvementsin Methods of lPreparing Crucibles for Preparing Fused Quartz, of whichthe following is a specification.

My invention relates to the art of preparing fused quartz which is usedfor the making of manykinds of articles, for example, for containers formercury vapor electric apparatus. My invention covers more particularlythe preparation of a crucible adapted for the fusing of this material.@ne of the difficulties met in the treating of very refractorysubstances, of which silica is only one representative, is the obtainingof crucibles suitable for withstanding the high temperatures involvedand at the same time to be neutral with regard to the sub stances beingfused or heated. It is well known that carbon or graphite resists heatin a very satisfactory manner at these high temperatures where no oxygenis present to combine with the carbon, but for many substances carbon isan undesirable material for a crucible on account of its tendency toreact chemically upon them. Many substances will form carbids under thecondition of high temperature when in contact with carbon.

My plan is to utilize carbon for its excellent heat resisting power, itschemical qualities, its cheapness and the facility with which it may beworked and to prevent reaction between the crucible and the charge bykeeping the two out of contact as by the insertion of a tight liningbetween the charge and the exposed wall of the crucible. l have foundthat among the various materials that may be used for such a lining andwhich are inert with regard to various.

substances that may be operated upon, such as fused silica, a productobtained from a compound of tungsten is of great value. In virtue of itsrefractory nature, however, tungsten is not only expensive but diilicultto manipulate and is hardly known in large thin pieces.

My invention includes, however, a method for producing a tight lining ina carbon or graphite crucible or crucible of similar materlal whlch 1scheap and effective. My process and the apparatus used inthis applicationare shown in the accompanying drawings in which Figure 1 shows thecrucible finished with a quantity of fused material therein; Fig. 9shows a fragment of the crucible in the initial stage of thepreparation; and Fig. 3 shows the finishing stages.

In the first figure, 1 represents a hollow carbon or graphite shell orfoundation so shaped as tostand firmly on a base and to hold the desiredquantity of charge. l 2 represents the charge chamber, 3 the tungstenlining and 4t the molten charge which may be, as already described,ofsilica. The lining, 3, is tight to prevent any contact besodiumtungstate with some solvent or hinder such, for example, as sodiumsilicate and apply this paste intimately to the surface of the crucible.This mixture contains tungsten, sodium, silica and water. This stage ofthe preparation is shown in Fig. Q.

.When the paste has become somewhat dry I heat it, gradually raising thefiring higher and higher. If this is fired sufficiently high, theresiduum is refractory and inert chemically. To transform the rough,spongy sur face to a smooth, closed surface, I may use a spinning toolas shown in Fig. 3 applied while the lining is hot in which state it isplastic and can be spun as shown in this figure. I may use for thisspinning any of the usual spinning devices such, for example, as a highvelocity wheel carried in bearings which can be guided or applied byhand, if desired.

In Fig. 2, l is the carbon of the crucible described above and 5 is theunheated mixture of paste of sodium tungstate and sodium silicate, shownas applied on a small surface of the crucible, and in Fig. 3 which showsthe crucible after the firing, 6 is the rough or frittered surface ofthe lining, 7 is a portion of the finished surface, 8 is the spinningwheel, 9 the bearings for the spinning Wheel,'l0 the handle, 11 a pulleyon the shaft of the wheel 8, and 12 a belt for driving the pulley-athigh speed. WVhen the Whole surface has been gone over like the surface7 of Fig. 3, the crucible is complete and ready for'u'se.

It is ell oftentimes in carrying out the heating or igniting of thecrucible and the paste to keep the crucible in a reducing atmosphere, asfor example an atmosphere of hydrogen to prevent the injurious effectofoxygen on the lining. I

Ihave described a product obtained from a tungsten compound as amaterial for the lining of my crucible but do not wish to be limited'tothis material for there are other refractory chemically inert materialsvery well adapted for certain uses of my apparatus. Neither do I Wish tolimit myself to carbon for other refractory material which needs alining or any material which maybe substituted therefor falls Within thescopeofthe present invention. Neither do i's 0.00'0'0035 and that thatof graphite is of the same order of magnitude, that the lining in thecrucible will not be unduly strained by expansion and contraction. IWould recommend a temperature of a thousand degrees centigrade or higherfor the spinning of the lining.

This case is a division of my application Serial Number 776,756, filedJuly 1st, 1913. .I claim as my invention:

1. The method of forming a crucible for fusing refractory materialswhich consists in lining a carbon shell with a paste containing arefractory metal compound and a suitable binder,.igniting said paste andsaid shell, and spinning or rubbing the residue of the paste to producea more firm and compact surface thereon.

2. The method of preparing a crucible for the preparation of fusedquartz which consists in preparing a carbon shell for said crucible andpreparing a paste of tungstate of sodium and a suitable binder, puttingthis paste over the inner surface of the carbon shell, igniting thecrucible, and spinning or rolling down the residual residuum to form aclosed tight surface.

Signed at New York in the county of New York and State of New York this1st day of April, A. D. 1915 FREDERICK G. KEYES.

Witnesses:

WM. H. CArnL, THos. H. BROWN.

copiesefithisipatent may be obtained for five cents each, by addressingthe Commissioner of Patents,

v Washington, D. 0.

